The Canon EF-S 15-85mm has undoubtedly produced some excellent pictures, but it's beginning to wear on me a bit. The most frequent complaint from everyone who was or is skeptical of it is the aperture to which I may not have given enough thought. I don't label myself as "into" low light photography but there have been many times over my ~2 years of ownership that I had to use uncomfortably high ISO's and would have really loved a faster aperture. On top of that, it is put together quite carelessly. It was somewhat elegant at first, but over time the barrel creeps, I can feel and hear the zoom barrels wobbling when I pick it up, and what put me over the edge in terms of build quality - recently the silver ring completely peeled off. This is not the mere loss of an aesthetic nicety; I either have to have it halfway on in a wrinkled, unsightly way, or deal with sticky adhesive right where I hold the zoom control. All this combined has made the 17-55/2.8 a lot more tempting. In fact, I really wasn't even considering it during my early stages of photography (when I selected the 15-85), partly because of the price but also because I didn't fully realize the benefits of fixed apertures. I've been surprised that it isn't just dim bars and indoor concerts - even when the sun starts to go down in a routine outdoor shoot it becomes a challenge. The 50mm f1.8 is worth what you pay for it with and is no substitute for a fast zoom.

But here's the thing - people hesitate to buy the 17-55 because of its more limiting range. But looking back over my experiences with the 15-85mm, I seldom go over 50mm or so. Sure, it's nice to have in case, but I might be paying a premium for convenience. I love to shoot, for lack of a better word, "vast" things like landscapes and architecture. This sort of rules out a 24-105 even though I would love the mechanical quality of an L. We all want to have variety in our work but I would not really be lost without the long end (mind you, at 5.6 it's only sometimes usable anyway) and when I need to get close I own a Tamron 70-300VC which has a focus mechanism from hell but can produce really pleasing results. From what I've seen the 17-55 would also provide appreciable improvement for color fringing and vignetting, as well as being a tad bit sharper. Even though the new lens seems amazing, it's not an exact trade-off and would still be somewhere around $400 extra after I sell my 15-85. I'd say I'd be doing good to start using a full frame DSLR 5 years from now, definitely not in the plans for the near future. Does this make sense for my situation to have constant f2.8, slightly more reliable build, and more precise optics?

To me the function of a standard zoom is to provide a flexible tool. It can't do everything. Now, if a f/2.8 lens is enough of a difference is down to the user. To me, I either want zoom, or aperture. For the latter, a fast zoom doesn't quite cut it, and I'd look at primes instead, although there are not too many affordable options on the wider end.

I can relate to your thinking, I was going through a similar thought process. I nearly bought the 17-55 ism usm or the tamron non vc 17-50. I was after a bit more low light ability and more dof.I didn`t want to sell the 15-85, because its such a versatile lens, even more when coupled with a flash.

Ever since I have bought the 30 1.4 Sigma, I haven`t had the urge to buy anything else, so agree with popo have a look at a prime lens.

Reading the original post, and the replies, made me think again of the new 28mm lens with IS, which has been reviewed quite favorably, regarding the quality of its optics, and also of the 35mm 1.4L lens, the latter being a highly-favored prime on my cropped-frame Canons. A quite inexpensive option would be the 40mm 2.8 STM, which I love on full-frame and 1.3x crop-factor Canons, but have yet to really try on my 7D or 5D cameras. The "shorty forty" pancake lens is a truly good little lens, a better bang for the buck than any Canon lens, in my opinion, but I am inexperienced with it on 1.6x-crop, where it is equivalent to 60mm+.

I have no hands-on experience with the 15-85mm or 17-55mm, nor the EF 28mm with IS, though the latter is near the top of my wish list. I briefly owned the older EF 28mm 2.8, and deeply regrettrading it.

Knowing from an early point in time that I would try full-fame, I have avoided purchasing EF-S lenses, except for the excellent 10-22mm.

Renting/hiring/borrowing a prospective lens for a week might be a consideration! This would lessen the likelihood of remorse after selling or trading an older but good lens, and then being disappointed in a newer one.

Thanks all. Still don't have a strong conviction either way but I think I'll just keep the money.

P.S. would you expect the missing ring to have any notable effect on resale value? There is also a very slight bit of residue on the bottom from where I tried to superglue it as it started to peel off (even that couldn't save it ). Just a little worried that it will appear I didn't take care of it well or something. It pains me to have to use it with the compromised appearance because I have never been disappointed by the IQ. But I'm enough of a technological nerd where these little fit & finish things drive me crazy. What about other people, "normal" people on ebay or wherever, is this a very big deal or will it still only matter about the function and results?